Android中经常会遇到对图片进行二次处理，例如加圆角，或者显示圆形图片

实现的效果图：

方法一：

通过第三方框架Glide实现图片显示有圆角，有三种写法如下：

1.1、第一种实现：

RequestOptions options = new RequestOptions().error(R.drawable.img_load_failure).bitmapTransform(new RoundedCorners(30));//图片圆角为30Glide.with(this).load(URL) //图片地址 .apply(options) .into(ImagView);

1.2、第二种实现：

RequestOptions requestOptions = new RequestOptions();requestOptions.placeholder(R.drawable.ic_launcher_background);requestOptions.circleCropTransform();requestOptions.transforms( new RoundedCorners(30));Glide.with(this).load(URL) //图片地址 .apply(options) .into(ImagView);

1.3、第三种实现：

RequestOptions options = new RequestOptions().centerCrop() .transform(new RoundTransform(this,30)); Glide.with(this).load(URL) //图片地址 .apply(options) .into(ImagView);public class RoundTransform extends BitmapTransformation { private static float radius = 0f; public RoundTransform(Context context) { this(context, 4); } public RoundTransform(Context context, int dp) { super(context); this.radius = Resources.getSystem().getDisplayMetrics().density * dp; } @Override protected Bitmap transform(BitmapPool pool, Bitmap toTransform, int outWidth, int outHeight) { Bitmap bitmap = TransformationUtils.centerCrop(pool, toTransform, outWidth, outHeight); return roundCrop(pool, bitmap); } private static Bitmap roundCrop(BitmapPool pool, Bitmap source) { if (source == null) return null; Bitmap result = pool.get(source.getWidth(), source.getHeight(), Bitmap.Config.ARGB_8888); if (result == null) { result = Bitmap.createBitmap(source.getWidth(), source.getHeight(), Bitmap.Config.ARGB_8888); } Canvas canvas = new Canvas(result); Paint paint = new Paint(); paint.setShader(new BitmapShader(source, BitmapShader.TileMode.CLAMP, BitmapShader.TileMode.CLAMP)); paint.setAntiAlias(true); RectF rectF = new RectF(0f, 0f, source.getWidth(), source.getHeight()); canvas.drawRoundRect(rectF, radius, radius, paint); return result; } public String getId() { return getClass().getName() + Math.round(radius); } @Override public void updateDiskCacheKey(MessageDigest messageDigest) { }}

方法二：

自定义ImageView：

<ImageView android:id="@+id/iv" android:layout_width="300dp" android:layout_height="300dp" android:layout_centerHorizontal="true" />ImageView iv = findViewById(R.id.iv); Bitmap bitmap =BitmapFactory.decodeResource(getResources(), R.drawable.fengjing); Bitmap outBitmap =getRoundBitmapByShader(bitmap, 500,300,20, 3); iv.setImageBitmap(outBitmap);public class RoundRectImageView extends ImageView{ private Paint paint; public RoundRectImageView(Context context) { this(context,null); } public RoundRectImageView(Context context, AttributeSet attrs) { this(context, attrs,0); } public RoundRectImageView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); paint = new Paint(); } /** * 绘制圆角矩形图片 * @author caizhiming */ @Override protected void onDraw(Canvas canvas) { Drawable drawable = getDrawable(); if (null != drawable) { Bitmap bitmap = getBitmapFromDrawable(drawable);// Bitmap bitmap = ((BitmapDrawable) drawable).getBitmap(); Bitmap b = getRoundBitmapByShader(bitmap,getWidth(),getHeight(), 50,0); final Rect rectSrc = new Rect(0, 0, b.getWidth(), b.getHeight()); final Rect rectDest = new Rect(0,0,getWidth(),getHeight()); paint.reset(); canvas.drawBitmap(b, rectSrc, rectDest, paint); } else { super.onDraw(canvas); } } /** * 把资源图片转换成Bitmap * @param drawable * 资源图片 * @return 位图 */ public static Bitmap getBitmapFromDrawable(Drawable drawable) { int width = drawable.getIntrinsicWidth(); int height = drawable.getIntrinsicHeight(); Bitmap bitmap = Bitmap.createBitmap(width, height, drawable .getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565); Canvas canvas = new Canvas(bitmap); //drawable.setBounds(-4, -4, width + 4, height + 4); drawable.draw(canvas); return bitmap; } public static Bitmap getRoundBitmapByShader(Bitmap bitmap, int outWidth, int outHeight, int radius, int boarder) { if (bitmap == null) { return null; } int width = bitmap.getWidth(); int height = bitmap.getHeight(); float widthScale = outWidth * 1f / width; float heightScale = outHeight * 1f / height; Matrix matrix = new Matrix(); matrix.setScale(widthScale, heightScale); //创建输出的bitmap Bitmap desBitmap = Bitmap.createBitmap(outWidth, outHeight, Bitmap.Config.ARGB_8888); //创建canvas并传入desBitmap，这样绘制的内容都会在desBitmap上 Canvas canvas = new Canvas(desBitmap); Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG); //创建着色器 BitmapShader bitmapShader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP); //给着色器配置matrix bitmapShader.setLocalMatrix(matrix); paint.setShader(bitmapShader); //创建矩形区域并且预留出border RectF rect = new RectF(boarder, boarder, outWidth - boarder, outHeight - boarder); //把传入的bitmap绘制到圆角矩形区域内 canvas.drawRoundRect(rect, radius, radius, paint); if (boarder > 0) { //绘制boarder Paint boarderPaint = new Paint(Paint.ANTI_ALIAS_FLAG); boarderPaint.setColor(Color.GREEN); boarderPaint.setStyle(Paint.Style.STROKE); boarderPaint.setStrokeWidth(boarder); canvas.drawRoundRect(rect, radius, radius, boarderPaint); } return desBitmap; } }

方法三：

对图片进行处理，此方法还可以加边框

/** * 通过BitmapShader实现圆形边框 * @param bitmap * @param outWidth 输出的图片宽度 * @param outHeight 输出的图片高度 * @param radius 圆角大小 * @param boarder 边框宽度 */public static Bitmap getRoundBitmapByShader(Bitmap bitmap, int outWidth, int outHeight, int radius, int boarder) { if (bitmap == null) { return null; } int height = bitmap.getHeight(); int width = bitmap.getWidth(); float widthScale = outWidth * 1f / width; float heightScale = outHeight * 1f / height; Matrix matrix = new Matrix(); matrix.setScale(widthScale, heightScale); //创建输出的bitmap Bitmap desBitmap = Bitmap.createBitmap(outWidth, outHeight, Bitmap.Config.ARGB_8888); //创建canvas并传入desBitmap，这样绘制的内容都会在desBitmap上 Canvas canvas = new Canvas(desBitmap); Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG); //创建着色器 BitmapShader bitmapShader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP); //给着色器配置matrix bitmapShader.setLocalMatrix(matrix); paint.setShader(bitmapShader); //创建矩形区域并且预留出border RectF rect = new RectF(boarder, boarder, outWidth - boarder, outHeight - boarder); //把传入的bitmap绘制到圆角矩形区域内 canvas.drawRoundRect(rect, radius, radius, paint); if (boarder > 0) { //绘制boarder Paint boarderPaint = new Paint(Paint.ANTI_ALIAS_FLAG); boarderPaint.setColor(Color.GREEN); boarderPaint.setStyle(Paint.Style.STROKE); boarderPaint.setStrokeWidth(boarder); canvas.drawRoundRect(rect, radius, radius, boarderPaint); } return desBitmap;}

实现圆形和边框：

/** * 通过BitmapShader实现圆形边框 * @param bitmap * @param outWidth 输出的图片宽度 * @param outHeight 输出的图片高度 * @param boarder 边框大小 */public static Bitmap getCircleBitmapByShader(Bitmap bitmap, int outWidth, int outHeight, int boarder) {int radius;int width = bitmap.getWidth();int height = bitmap.getHeight();float widthScale = outWidth * 1f / width;float heightScale = outHeight * 1f / height; Bitmap desBitmap = Bitmap.createBitmap(outWidth, outHeight, Bitmap.Config.ARGB_8888);if (outHeight > outWidth) { radius = outWidth / 2;} else { radius = outHeight / 2;}//创建canvasCanvas canvas = new Canvas(desBitmap);Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);BitmapShader bitmapShader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);Matrix matrix = new Matrix();matrix.setScale(widthScale, heightScale);bitmapShader.setLocalMatrix(matrix);paint.setShader(bitmapShader);canvas.drawCircle(outWidth / 2, outHeight / 2, radius - boarder, paint);if (boarder > 0) { //绘制boarder Paint boarderPaint = new Paint(Paint.ANTI_ALIAS_FLAG); boarderPaint.setColor(Color.GREEN); boarderPaint.setStyle(Paint.Style.STROKE); boarderPaint.setStrokeWidth(boarder); canvas.drawCircle(outWidth / 2, outHeight / 2, radius - boarder, boarderPaint);}return desBitmap;}

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